The invention relates to teat cup assemblies for vacuum-operated milking machines and, more particularly, to liners or inflations for teat cup assemblies including an end portion attached to the nipple of the milking machine claw.
The teat cup assemblies for vacuum-milking machines include a liner or inflation having one end connected to a nipple on a so-called claw of the milking machine. During normal operation, the teat cup assembly is suspended from the teat of the cow and milk flows through the inflation under the influence of a vacuum maintained in the claw. When a teat cup assembly is removed from the cow's teat, either accidently or intentionally upon completion of milking, the inflation is suspended from the claw nipple in a manner to shut communication between the claw and the inflation and thereby preserve the vacuum in the system. This is accomplished by arranging the inflation so that the inner wall sealingly engages the end of the claw nipple or the walls crimp together at a location beyond the claw nipple. In either case, the inflation is bent in the region of the claw nipple and this portion is vulnerable to impacts by the cow, objects, equipment, etc. which can cause cuts, splits or tears with a resultant reduction in service life of the inflation.
Representative prior inflation constructions designed to minimize this problem are disclosed in U.S. Pats. Nos. 2,009,884 (Green) issued Nov. 23, 1937, 2,341,953 (Scott) issued Feb. 15, 1944, 2,694,379 (Hein) issued Nov. 16, 1954, 3,611,993 (Norton) issued Oct. 12, 1978 and 4,196,696 (Olander) issued Apr. 8, 1980.
The Hein patent discloses an inflation which includes a weakened wall section to facilitate crimping for shutoff but does not include any external reinforcement means for protection against impacts in the region near the outer end of the claw nipple.
The Scott and Norton patents disclose inflations which respectively include and external bead and a thickened wall section in the region near the end of the claw nipple. Such an external bead provides only a limited area of protection and a thickend wall portion reduces flexibility to the point where a complete shutoff may not occur under some circumstances.
The Green patent discloses an inflation including a plurality of axially-spaced, circumferentially-extending external ribs. While such ribs minimize the loss of flexibility and provide some protection against impacts, the thinner, stretched areas between the ribs are unprotected. Thus, these areas are vulnerable to impacts striking the claw end of the inflation in a direction extending transversely of the claw nipple.
The Olander patent discloses an inflation including a thickened wall section including a plurality (preferably 12 or more) of axially-extending, circumferentially-spaced external projections. The combined effect of the thickened wall section and the external projections substantially reduces flexibility which can reduce the shut off capability and the gripping action of the inflation on the claw nipple.